DSLWP-B camera field of view

In my previous post, I wondered about what was the field of view of the Inory eye camera in DSLWP-B. Wei Mingchuan BG2BHC has answered me on Twitter that the field of view of the camera is 14×18.5 degrees. However, he wasn’t clear about whether these figures are measured from the centre of the image to one side or between two opposite sides of the image. I guess that these values are measured from the centre to one side, since otherwise the total field of view of the camera seems too small.

Here I measure the field of view of the camera using the image of Mars and Capricornus taken on August 4, confirming that these numbers are measured from the centre of the image to one side, so the total field of view is 28×37 degrees.

The first image taken by the DSLWP-B Inory eye camera was a picture of the sky including Mars and the constellation of Capricornus. It was taken on 2018-08-04 15:30 UTC and downloaded later. This image is shown below in enhanced contrast with some of the stars identified.

Image of Mars and Capricornus (enhanced contrast)

The distance between Mars and β Aquarii in the image above is 454 pixels. Using Astropy we compute in this Jupyter notebook the separation between Mars and β Aquarii to be 26.5 degrees. Since the full image is 640×480 pixels, this amounts to 37.36×28.02 degrees, which is very close to the value of 37×28 degrees mentioned above. This measurement confirms the field of view of the camera.